Electromagnetic switching device



Oct. 19, 1931. J, s, GARWN 2,096,456

ELECTROMAGNETIC SWITQHING DEVICE Filed April 16, 1935 FIG! F/GZ INVENTORBy J. $.GARV/N A TTORNEY Patented Oct. 19, 1937 UNITED STATES PATENTOFFICE Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application April 16, 1935,Serial No. 16,579

3 Claims.

This invention relates to electromagnetic switching devices and moreparticularly to means for improving the release characteristics ofelectromagnetic relays.

5 The correct functioning of electric circuits generally, and telephonecircuits particularly, depends to a major degree upon the accurateoperation of the switching devices used to control such circuits.Electromagnetic relays are de- 10 signed and adjusted to exhibitdefinite time operating characteristics. That is, a relay underfavorable conditions will operate or release at a definite timefollowing the energization or deenergization of the relay magnet, eitherimmediate- 15 ly or, in the case of slow-acting relays, shortly afterthe closure or opening of the relay circuit.

In order that switching devices serve in a precise manner the purposefor which they are employed, it is essential that the elements thereof,

so such as the armature and core between which mutual attraction existswhen the electromagnet is energized, be free from foreign matter, suchas dust, dirt, etc., which causes sticking.

It is the object of this invention to improve the 25 operatingcharacteristics of electromagnetic switching devices by precluding thepossibility of an accumulation of dust, dirt or other foreign matter oncooperating pole faces of such devices.

This object is attained in accordance with a so feature of the inventionby the provision of a metal separator which may be readily insertedbetween the oppositely disposed pole faces of the armature and core.

Another feature of the invention resides in so 35 designing and mountingthe separator that it insures the dislodgment of foreign matter whichmay settle on the contacting surfaces of the armature and core, therebyminimizing the tendency to stick.

These and other features of the invention will be readily understoodfrom the following detailed description made with reference to theaccompanying drawing, in which:

Fig. 1 is a front end view of a relay illustrating 45 the relativedisposition of the separator and the relay armature and core;

Fig. 2 is a fragmentary plan view of the relay shown in Fig. l

Fig. 3 is a fragmentary view similar to that of 50 Fig. 2 in which therelay armature, contact springs and adjusting nut have been omitted; and

Fig. 4 is a perspective view of a particular form of separator.

55 The separator ill of this invention is a detail of lightweight metal,such as phosphor bronze, which may be stamped or otherwise formed toprovide it with a shape suitable for use with a particular type ofswitching device. It may be necessary, in order to satisfy structuralpeculiari- 5 ties or characteristics of certain relays to modify theform of separator shown in Fig. 4. This may be done without departingfrom the spirit or scope of the present invention, it being understoodthat the particular types of relay and separator shown have beenselected as being illustrative of one embodiment of the invention only.

The separator I!) which is substantially L-shaped is provided with asemi-circular notch or indent H and a flat lug or tab 12 integrally as-15 sociated therewith and extending at right angles therefrom. By virtueof the notch l l and lug [2, the separator I0 is floatingly mounted onthe relay core I3 in the following manner. The separator is insertedbetween the core l3 and armature 14 so that the lug l2 extends at rightangles to the longitudinal axis of the core I3 and rests upon the upperedge thereof. The separator may then be shifted in either directionalong the upper edge of the core until the air-gap adjusting screw I5engages the notch II. This position of the separator on the relay coreis clearly illustrated in Fig. 3.

The length of the lug I2 is greater than the length of the normalair-gap between the relay armature and core in order to insure againstthe falling of the separator through the gap, it being understood thatthe separator I0 is not rigidly fixed but is free to move away from thecore with the core edge and adjusting screw as points of support.

When armature l 4 is actuated as a consequence of the energization ofthe relay coil IE, it approaches the core l3 and on its travel engagesthe separator In which may be in the position shown in Fig. 1 or in aposition further removed from the core I3. In any event, due to the factthat the separator is not fixed and is free to move relative to the coreand armature, it effects a wiping action on the core and armaturesurfaces thereby minimizing the possibility of dirt accumulating oneither of these surfaces to cause sticking. When the energizing force isremoved from the coil IS, the armature restores to normal and in pullingaway from the core causes the separator to be moved slightly, oragitated. It'is evident, therefore, that the floatingly mountedseparator moves relative to the core and armature both on the operateand release strokes of 55 the armature to produce a cleansing action onthe Surfaces thereof.

The introduction of the separator between the armature and core alsoincreases the number of 5 contacting surfaces upon which an accumulationof dirt is necessary before a sticking condition The possibility ofsticking is accordmagnet is energized, said means comprising a metaldetail having allug for engagement with an edge of said core and anindent for engagement with said screw whereby said detail is float.- 20ingly supported in'said air-gap.

2. In an electromagnetic switching device, an'

electromagnet having a core, an armature, said core and armature beingseparated by an airgap of predetermined length and a metal detaildetachedly sup-ported in said air-gap by means of an integral lugresting on the edge of said core 5 and. extending in a directioncorresponding to the line of travel of said armature, said lug having alength greater'than the length of said air-gap.

3. In an electromagnetic switching device, an electromagnet having acore, an armature, said core and armature having pole faces separated byan air-gap, means for-adjusting'said air-gap including a screw, asheet-like detail located in said air-gap and detachedly supported onsaid core and said screw, opposite surfaces of a said detail makingsurface contact with the pole faces of said armature and corerespectively when said electromagnet is energized, and means forenergizing saidelectromagnet.

' JOHN S. GARVIN. 20

